Crown-tooth



J. L. WILLIAMS.

CROWN TOOTH.

APPLICATION FILED JAN.29,1920- 1,397,067. A Patented Nov. 15,1921.

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JAMES LEON WILLIAMS, OF NEW YGRK, N. Y., ASSIGNOR TO THE DENTISTS SUPPLYCOIVIPANY. A CORPORATION OF NEW YORK.

CRO NN-TOOTH.

nearest.

Application filed January 29, 1920.

To all "whom it may concern.

Be it known that I, Jiuuns LEON VVILLIAMs, a citizen of the UnitedStates, and resident of New York city, county of New York, and State ofNew York, have invented an Improvement in Crown-Teeth, of which thefollowing is a specification.

Heretofore, the construction of crown teeth, employing pins forattachment to roots, have not been proportioned or shaped properly togive the greatest possible strength, and this also applies to the pin,as to its shape on that part which enters the hole or recess in theporcelain tooth.

At the neck, the greatest diameter of the anterior teeth (for which thegreat majority of porcelain crowns are made) is bucco-lingually, but thegreatest diameter of the incisal half of the crown is in the opposite direction, that is to say, mesio-distally; and by reason of this fact,objection arises to the old style of pin (which, in the part enteringthe crown, is of the same diameter throughout), because the hole whichreceives the pin, if continued a sufficient depth into the porcelain tomake the hold secure, often and especially in short teeth, nearly cutsthrough the lingual surface of the porcelain tooth and thereby greatlyweakening it. It is also often found necessary in order to get properocclusion, to grind the lingual surface of the porcelain crown and indoing this the pin hole is sometimes exposed through the tooth wall.Thus, by the removal of porcelain to the pin hole and by the exposure ofthe cement which fastens the pin to the crown and the disintegratingaction of the saliva, there results a double weakening of crown andattachment.

The object of my invention is to provide a construction of crown toothand pin structure adapted thereto which will overcome the objectionsabove pointed out as existing in'the structures at present in commonuse.

In my invention, that portion of the pin entering the porcelain isshaped to correspond with the shape of the crown, and like the crown, itis thin bucco-lingually and wide mesio-distally at the lower end. Whilecontaining even more metal than the round pin yet by being flattened atits lower extremity it can be made to pass deeper into the porcelaincrown; and on the principles of leverage, a little additional length ofJ pin adds greatly to the security of the at- Specification of LettersPatent.

Patented Nov, 15,1921.

Serial No. 354,980;

tachment. *While firmer attachment is thus secured, the substance of theporcelain is at the same time conserved so that considerable grinding onthe lingual surface of the tooth can bedone without materially weakeningit.

My invention further embodies a crown tooth with a large flattenedrecess about the pin hole and with undercut side walls and in which awide annular shoulder on the pin tits and is securely cemented therein.The deep hole into which the pin extends is also undercut and likewiseinsures a stron attachment. O A. further feature of improvement residesin making the crown at the buccal side with a full height, but on thelingual side cutting away the neck of the crown sufliciently to givespace for the metal coping and thereby making it easy for thedentist tofit the crown to the root, since the only actual fitting of the toothitself will be at the buccal edge.

I also direct attention to the fact that this same crown may be used onvulcanite or gold plates or on fixed or removable bridges, these usesonly requiring the portion of the pin above the shoulder to be formed orshaped to suit the particular character of work to be made, all of whichwill be more clearly understood from the description hereinafter.

My invention also consists of improve me'nts hereinafter describedwhereby the above objects and results are attained, said improvementscomprising certain organization and combination of parts which are fullydescribed hereinafter and more particularly defined in the claims.

Referring to the drawing: Figure l is a vertical section,bueco-lingually, of a crown embodying my invention fitted to a naturalroot Fig. Qis a vertical section, mesio-distally, of the crown and pinembodying my invention before being fitted to the tooth root; Fig. 3 isa plan view, looking downward upon my improved crown (with the pinremoved); and Fig. l is a-perspective view of my improved pin beforebeing applied to the tooth crown.

'2 is the tooth root, 3 is the porcelain crown, 4: is the attaching pin,and 5 is the metal coping between the crown and root.

The pin 4': comprises the long tapering part 16 which enters the hole 13in the natural root, the short pin portion 18, which enters the hole inthe porcelain crown, and the annular collar or shoulder 14. at thejuncture of the parts 16 and 18.

The short pin portion 18 is of somewhat larger diameter at its endadjacent the collar 14. than the root prong or pin part 16 and theportion is, furthermore, flattened at its end 20 so that at this part itis thin and wide, and when. fitted to the crown, the wide diameterextends mesio-distally of the crown. The portion 18 will be tapering inthe bucco-lingual direction (Fig. 1), but fantail in shape in themesio-distal direction, the greatest width being at or near the endwhich is received in the bottom part of the hole in the crown, (Fig. 2).The pin part 16 is provided with several annular grooves 17, the pinpart 18 with annular grooves 19, and the collar with an annular groove15, the several grooves being intended to receive the cement and morepositively retain the pin structure in position.

The crown 3 is shaped to correspond to the natural shape of the exposednatural tooth beyond the neck, except that in my improved crown, theneck portion to the rear of the buccal edge 10 is cut down to the level11 in Fig. 1, to give space rearward to the lingual surface for themetal coping 5 which fills the space between the crown and root, asshown in Fig. 1. The hole 6 in the crown, at the point 7, where the pinenters, is oval in outline (Fig. 3) to admit the flattened and widenedend 20 of the pin portion 18. Both the recess 8, which receives theshoulder 141 of the pin, and the deeper part of the hole 6, areundercut. This undercut insures very secure locking of pin to crown,when the crown is cemented at 5 to the pin. This undercut for the recess8 is formed by the beveled side walls 9; and for the hole 6 the undercutis in the mesio-distal direction, as shown in Fig. 2.

This crown is designed to be used with a metal cap or a cast metalcoping, as above stated, and it is, therefore, necessary that thelingual part of the neck of the tooth be cut away, as at 11, to givespace for the metal coping 5; and this makes the fitting of the crownvery easy for the dentist, as the only fitting ever required will be atthe thin buccal edge 10. When this fitting of the buccal edge has beendone, a suitable piece of warmed wax is passed over the root end 16 ofthe pin, the pin in serted in the crown and the whole pressed to placeover the end of the root. The surplus wax is then trimmed away, thecrown removed and the pin with wax in vested for casting. The castingmay be made directly to the end of the root or to a metal cap which hasbeen previously fitted to the end of the root, as will be readilyunderstood by dentists.

While I have specially illustrated my improved crown and engaging pinfor applipresent invention.

cation to the natural root, the same porcelain tooth may be used 011vulcanite or gold plates or on fixed or removable bridges, as may berequired. For all of these uses, the only necessary change is in theform of the upper end of the pin for the attachmentto the plates orbridges. For gold plate and bridge work, it is merely required that aportion of the root end of the pin be cut off. and then the pin withtooth in position may be fitted to place. The tooth is then removed andthe pin soldered or otherwise made fast to the plate or bridge, afterwhich, the crown may be cemented to the pin.

in all uses of this tooth, the porcelain is never subjected to the risksof breakage by the heat of the soldering or casting processes Theporcelain is always removed, after the necessary fitting, until thecasting or soldering process is completed, after which. the crown isattached-to its pin by cementing.

In using this tooth for vulcanite plates, a slightly different form forthe pin above the shoulder 14 is required, this being to provide asuitable head or anchoring part, to become embedded in the vulcanitevery mu h as headed pins of soldered pin teeth are embedded forattaching teeth of that character to vulcanite plates, but thisparticular feature need not be described in detail, as it forms nospecific part of the I Reference is made to such use, however, asshowing the adaptability of my improved crown and pin structure directlyattached thereto for all possible required uses in practice.

Among the more particular advantages resulting from this form of toothmay be mentioned the following: That as a tooth for plates, crown andbridges, it is strong and secure in its attachment, this strength andsecurity of attachment being attained by the mechanically correct shapeof the pin in relation to the crown, the dovetail form of the crown end20 of the pin and the corresponding undercutting of the pin cavity G inthe crown; the great simplicity and ease of adjustment due to the factthat the only fitting required is on the thin buccal edge which iseasily ground, the back being cut away to receive the wax for the.casting process; its adaptability for vulcanite plate work and as suchis far stronger than any tooth with baked-in or soldered pins can bemade; and as a tooth for plate work, the tooth has the advantage ofhaving the same shape and conformation as the natural tooth, includingthe lingual surface, by reason of which the patient, in speech may avoidcauses which produce lisping or thickness of speech, and secure generalcomfort in the use of the tongue, and in ease .of cleanliness.

In case of breakage from any cause, my improved crown may be easilyreplaced in a few minutes by merely clearing away the remains of thebroken tooth and cementing a new one in its place, and this applies toall of the special uses of the tooth, whether for natural roots, metalplate and bridge work, or for vulcanite work.

It will now be apparent that I have devised a novel and usefulconstruction which embodies the features of advantage enumerated asdesirable, and while .I have in the present instance shown and describedthe preferred embodiment thereof which has been found in practice togive satisfactory and reliable results, it is to be understood that I donot restrict myself to the details,

as the same are susceptible of modificationin various particularswithout departing from the spirit or scope of the invention.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

l. A crown tooth having the hole in its body made wider at its inner endin a direction mesio-distally of the tooth than at its outer or open endand at said outer end having the hole wider in a mesio-distallydirection than in a bucco-lingual direction, and further having the holeof an oval shape in cross section at its outer end and gradually reducedin bucco-lingual direction and widened in the mesio-distal direction toprovide a narrow and elongated cross section at the inner end.

2. The invention according to claim 1, having the open end of the holesurrounded with a shallow recess of greater diameter than the hole andhaving abrupt undercut side walls.

3. The invention according to claim 1, combined with a pin cemented inthe hole and having its lower end flattened and of a width greater thanits upper portion, said lower portion being of a less width than thesmallest diameter of the hole mesio-distally of the tooth, whereby thepin is securely attached to the crown and the latter is firmly heldagainst rotation upon the pin.

t. A crown tooth having the hole in its body made wider at its lowerpart mesiodistally of the tooth than at its upper part,

combined with a pin having an annular collar fitting the upper part ofthe tooth and an extended shank of smaller diameter flat tened at itsend and fitting into the hole in the tooth, said pin secured to thetooth by cement.

5. A crown tooth having a hole extending into its body and openingthrough the top thereof, said hole at the bottom having a widthmesio-distally greatly exceedingthe width bucco-lingually to provide aflattened recess and further having a shallow recess surrounding itsopen end, said recess having undercut side walls.

6. The invention of claim. 5, combined with an anchor pin having itslower part flattened and fitting the hole in the tooth and having anannular collar fitting the shallow undercut recess, said pin and itscollar cemented in place in the tooth.

7. A crown tooth having a hole extending into its bottom and openingthrough the top thereof, said hole at the bottom having a widthmesio-distally greatly exceeding the width bucco-lingually and graduallyflaring outwardly into an oval cross section in which the opening isgreater mesio-distally than bucco-lingually and in which further thehole at the bottom bucco-lingually is greatly less than the width of thehole at the open end bucco-lingually considered, in combination with ananchor pin having its end of flattened shape and its body approximatinga circular shape adjacent to the outer end of, the hole and said pinsecured in position within the hole by cement.

8. An anchor pin for a crown tooth, comprising a pin body having anannular collar, an extended part to one side of the collar having aflattened end, and an extended portion to the other side of the collarconstructed for attachment to a part to which the crown tooth is to besecured by the pin.

9. An anchor pin comprising a long tapered pin body having an annularshoulder provided with a peripheral groove, and further having ananchoring portion beyond the collar made flattened to provide a fantailstructure.

In testimony of which invention, I here unto set my hand.

JAMES LEON WVILLIAMS.

